Electric indicator.



No. 660,56l. Patented Oct. 30, I900.

C. L. CLARKE. ELECTRIC INDICATOR.

(Application filed July 1.0, 1900.)

2 Sheats--Sheai I.

(No Model.)

INVENTOR 6724/16; 1,. War/6e.

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No. 660,561. Patented Oct. 30, I900.

, c. L. CLARKE.

ELECTRIC lNDICATUR.

(Appfication filed July 10, 1900.) (No Model.) 2 Sheets$hfl0t 2.

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f? BY ATTORNEY UNITED STATES PATENT OFFICE.

CHARLES L. CLARKE, OF RYE, NEW YORK.

ELECTRIC IN DICATO R.

SPECIFICATION forming part of Letters Patent No. 660,561, dated October30, 1900.

Application filed July 10, 1900. Serial No. 23.100. (No model.)

T0 aZZ whom it may concern.-

Be it known that 1, CHARLES L. CLARKE, a citizen of the United States,residing at Rye, Westchester county, State of New York, have inventedcertain new and useful Improvements in Electric Indicators, of which thefollowing is a full, clear, and exact description.

My invention relates to improvements in electric indicators such asdescribed in my former application, Serial No. 1,717, filed January 17,1900, and has for its object the making of an apparatus for indicatingcertain phase and frequency relations in alternating-current systemswhich shall be more compact and convenient in arrangement andconstruction, more durable under continued operation, and more efficientin its action, and some of my improvements also havein view an apparatuswhich shall be applicable for use with both single-phase and multiphasesystems.

The following is a description of an apparatus embodying my invention,reference being had to the accompanying drawings, in which Figure 1 is afront elevation of my improved apparatus, and Fig. 2 is a side-elevationmidsectional view thereof.

Referring particularly to the drawings, A B O and A B 0 represent a pairof similar single-phase alternating-current motors, in this case eachmotor having six pairs of poles, in which a a are two s't r .gb 9 scopig d i s ks, (shutter-disk and target-disk, respectively,)

mounted on the rotatable shafts B B, which also carry the armatures A'A.These armatures are polarized so as to make alternate north and southpoles N S by a continuous current led to the coils N S thereon from thesource T by the two binding-posts t, four brushes t, and fourcollecting-rings t 0 C are two field-magnets of the respective motors,each of which has its windings D D connected, respectively, with thebindingposts d d and (1 d The binding-post d is not shown in thedrawings; but in Fig. 1 said binding-post is to be understood as beinglocated directly behind the binding-post d, just as d is located behind61, as shown in Fig. 2. The windings on the field-magnets are sodisposed as to make the alternate poles of each when energized ofopposite polarity, and let it be assumed that when a current flows in bythe binding-posts d and d and out by the binding-posts d and d theuppermost and lowermost poles and every second pole therefrom are ofnorth polarity and all the intermediate poles are of south polarity. Inthe rim of each of the disks a a, which are preferablyblackenedaluminium, are six slots, (as manyslots as there are pairs of poles ineach motor,) disposed at equia'ngular distances apart around the rim,those in the former (shuttendisk a) being markedf and those in thelatter (target-disk a) being marked f, and let it be assumed that saiddisks are so mounted on their shafts that the slots shall bediametrically in line with those poles of the armatures A A which are oflike polarity when the latter are energized by a continuous current, asbefore described. For example, let the shutter-disk. a be mounted on theshaft B, so that the slots fshall be dia metrically in line with southpoles S of the armature A, as shown in Fig. 1. In such case thetarget-disk a, is to be so mounted on the shaft B that the slotsf shallalso be diametrically in line with the south poles of the armature A.Behind these disks is a well-lighted white screen G, which when theslots in'the two disks are in line with the eye is visible and makes theslot in the targetdisk constitute a plainlyvisible white object. Abovethese disks a a is placed an ahgularly-adjustable two-part scaleconsisting of the front part h, substantially in the same plane as theshutter-disk 0t, and the rear part i, fixed to h and substantially inthe same plane as the target-disk a. The front part of the scale ismarked to read to one hundred and eighty degrees on either side of thezeroline, and the total width of the scale, which is three hundred andsixty degrees, embraces the one-twelfth part of the circumference of acircle, (that part of the circumference of a circle which is equal tothe whole circumference divided by twice the number of pairs of poles inthe motor,) as shown in Fig. l. The rear part of the scale has markingsd the same distance apart as the corresponding markings on 7t, so thatby keeping the eye in line with corresponding markings on both parts ofthe scale parallactic errors are avoided in reading the indications ofthe apparatus.

The part h of the scale has also upon it the words Fast, High, Leading,Slow, Low, Lagging, and two arrows, as shown in Fig. 1, the significanceof which will hereinafter appear.

The two motors have a common central support K, which is of iron orsimilar magnetic material and serves not only as a support, but also amagnetic shield for preventing the alternating field surrounding onemotor from exerting any disturbing effect upon the other. This supportis mounted on a base L by the brackets Z Z and carries the wholestructure, the outside members M M being secured thereto by posts N N.The two motors have their shafts mounted in ballbearings O O, and saidshafts extending through one bearing have knurled knobs P P, by whichthey may be impelled by hand, and in this manner the motors may bebroughtvup to synchronism.

In order to use my apparatus to indicate the phase and frequencyrelations of the electromotive force of an incoming single-phase dynamoto the electro motive force of the single-phase mains with which similardynamos in operation are connected, the binding-post d of the motor A BO is connected with one of the mains of the system, the binding-post dof the motor A B" O is connected with the corresponding lead of theincoming dy for connecting said dynamo with and disconnecting it fromsaid mainand the two other binding-posts cl and d of the motors areconnected with the remaining main and leads of the incoming dynamo,respectively, the armature-coils of the motors being energized from asource of continuous current. The motor A B O is then rotated clockwiserelatively to the scale by means of the knob P, and the motor A B O isrotated counterclockwise by means of the knob P, and in this manner bothmotors are brought into synchronous operation with the electromotiveforces of the circuits with which they are respectively connected. Thestroboscopic images caused by the slots ff and screens G (which imageswill be nearly white in color and substantially the same in appearanceas the White objects formed by the slots in the target-disk as seenagainst the screen) will under circumstances to be explained thenindicate certain frequency relations between the electromotive forces ofthe incoming dynamo and the system and when said frequencies are alikewill indicate what the phase rela- When tions of the electromotiveforces are. the total number of images formed is twelve (twice as manyimages as there are pairs of poles in each motor) and said images are atequiangular distances apart (in which case they will be three hundredand sixty degrees apart measured on the scale and not more than oneimage will be within the three-hundred-and-sixty-degree limits of thescale at the same time) and are rotating clockwise. the apparatusindicates that the polar speed of the incoming dynamo is a little slowerthan the polar speed of the dynamos connected with the mains, andconsequently that the electromotive force of the incoming dynamo is ofsomewhat lower frequency than that of the electromotive force of themains. The less this difference in frequency is the slower will be therotation of the images, and when the images are stationary the apparatusindicates that the frequencies are alike, and therefore that theincoming dynamo has the same polar speed as or is in synchronism withthe other dynamos connected with the mains. Rotation of the said twelveimages counter-clockwise indicates that the polar speed of the incomingdynamo is a little faster and the frequency of its electromotive forceis somewhat higher as compared with the speed and frequency for thedynamos already in the system. When the dynamos are in synchronism, andtherefore the said twelve images are stationary, the position of animage on the right of the zero-line of the scale indicates the degree'towhich the electromotive force of the incoming dynamo lags behindopposition with the electromotive force of the mains, it being assumedthat the scale has been adjusted beforehand by clamping it with itszero-line opposite an image, while both motors of the apparatus areoperated by currents derived from the mains by connecting thebinding-posts d d with one main and the binding-posts d d with the othermain, in whichcase the electromotive forces of said currents will be oflike frequency and in phase. Similarly the position of a stationaryimage on the left of the zero-line indicates the degree of lead. When animage stands at the Zero-point, theincoming dynamo will be running insynchronism and in phase or in step with the system.

It is obvious that by connecting the motor A B 0 across a line andinserting the motor A B O in the line the apparatus may be employed toindicate the phase relations of the electromotive force and current insaid line. It will also be seen that this single-phase electricalindicator can be used to give indications for multiphase apparatussimilar to such as have been hereinbefore described for singlephaseapparatus, if corresponding conductors of the multiphase apparatus areselected.

Many of the features of my invention are not confined to an indicatingapparatus employing single-phase-motor devices, and I do not wish to beunderstood as implying that they are not capable of embodiment in suchother apparatus.

What I claim is 1. In an electrical indicating apparatus the combinationof two alternating-current motors and a magnetic shield located betweenthem, substantially as described.

2. In an electrical indicating apparatus the combination of twoalternating-current motors, a stroboscopic system having each of itselements independently operated by one of said motors and a magneticshield located between said motors, substantially as described.

3. In an electrical indicating apparatus two alternating-current motors,having energizing-coils upon their armatures connected to a source ofcontinuous-current supply, and a stroboscopic system having each of itselements independently operated by one of said motors, substantially asdescribed.

t. In an electrical indicating apparatus the combination of twoalternating-current electric motors, two elements of a stroboscopicsystem each operated by one of said motors, and a screen behind saidelements.

5. In an electrical indicating apparatus the combination of twoalternating-current electric motors, stroboscopic disks operatedindependently thereby having slots in their peripheries and a screenbehind said slots, substantially as described.

6. In an electrical indicating apparatus the combination of astroboscopic system and means for independently operating the elementsthereof by alternating currents and a scale located near thestroboscopic images, substantially as described.

7. In an electricalindicating apparatus the combination of astroboscopic system two alternating-current motors for independentlyoperating the elements thereof and a scale l0- cated near thestroboscopic image provided with means for avoiding parallactic error.

CHARLES L. CLARKE.

Witnesses:

L. VREELAND, GEORGE T. HAOKLEY.

